1. The Field of the Invention
The present invention generally relates to optical communications networks. In particular, the present invention relates to systems and methods that provide redundant production and reception of channels in a multiplexed optical signal.
2. The Related Technology
Fiber optic technology is increasingly employed as a method by which information can be reliably transmitted via a communications network. Networks employing fiber optic technology are known as optical communications networks, and are marked by high bandwidth and reliable, high-speed data transmission.
Optical communications networks often employ a technique called wavelength division multiplexing (WDM) in order to maximize the amount of information that can be transmitted via the network. A plurality of optical transmitters are used at the transmission node of the optical network to transmit optical signals. Each optical transmitter receives an electric signal from a network device, such as a computer, and modulates the electric signal via a laser to an optical signal having a distinct wavelength, called a channel. The distinct channels from the plurality of optical transmitters are then combined by a multiplexor to form a multiplexed optical signal. The multiplexed WDM optical signal can then be transmitted via a single fiber optic cable to the optical network, such as a LAN backbone. The multiplexed optical signal is then received by a reception node of the network.
Once received by the reception node, the multiplexed optical signal is divided back into its constituent channels by a demultiplexor, and each channel is fed to one of a plurality of optical receivers for modulation into electrical signals. The electrical signals are then forwarded to a network device, such as a computer, for processing.
Though highly useful as a means for transmitting information, optical communications networks can occasionally suffer from certain device failures. For example, occasional failures can occur with either an optical transmitter in the transmitter bank, or an optical receiver in the receiver bank. When an optical transmitter fails, it fails to modulate the corresponding electrical signal into an optical signal channel, causing a void in the multiplexed optical signal. This can result in an undesirable loss of a significant amount of important data. Correspondingly, in the case of an optical receiver failure, the channel of the optical signal corresponding to the failed receiver is not converted into an electric signal, also resulting in an information void and unintended data loss. As may be appreciated, such transmitter or receiver failures can severely inhibit the effectiveness and operation of the optical communications network.
Known attempts for dealing with such transmitter failures have typically involved creating a full redundant set of backup optical transmitters, so that each channel has a primary transmitter and also has a backup transmitter which is used in the event of failure of the corresponding primary transmitter. Failure of optical receivers can also be managed using a similar full redundant set of backup optical receivers. Even though the use of a full redundant set of backup transmitters or receivers can reliably protect against the failure of a primary transmitter or receiver, the redundant system described above can be expensive to implement in an optical communications network. For instance, the use of redundant sets of backup optical transmitters or receivers doubles the number of transmitters or receivers in a transmission or reception node, since each channel has a primary and a backup component. This can dramatically increase the cost of optical networks so configured. Additionally, the full redundant sets of transmitters and receivers undesirably increase the complexity of the optical network.
A need therefore exists for a redundant optical communications network that can compensate for occasional optical transmitter or receiver failure by providing backup optical transmission and reception while avoiding the problems described above. Specifically, there is a need for an optical communications network having redundant transmission and reception capability that can be implemented in a simple and low-cost configuration.